Thermal conductivity and diffusivity measurements in the sub-mu m and sub-mu s scale on centimeter area samples using a microthermocouple

A micro-thermocouple, made of tungsten versus gold-0.07% Fe, is used in a scanning tunnel microscopelike setup to measure temperature profiles with submicrometer (100 nm) and submicrosecond (50 ns) resolution on centimeter (cm) area thin film surfaces. The installation is equipped with a new type of three-directional piezoelectric inertia drive and enables measurements in the temperature range from 4 to 300 K. The thermal conductivity of a 10 mu m gold foil and a silicon wafer (260 mu m) has been measured from 8 to 300 K and the thermal boundary resistances of GE-7031 varnish and In-foil, used to mount the samples, were determined. The measured temperature profiles, as a function of time and tip location on the sample, were modeled and fitted by the finite element method. The installation has been designed for mesoscopic temperature profiling to investigate thermal conductivity and diffusivity of thin films, multilayers, and thermal boundary resistances. The results for gold films agree with data reported in the literature. The importance of the boundary resistance (and boundary conditions) in heat flow experiments is emphasized. (C) 1996 American Institute of Physics.